Our efforts have been directed to the establishment of mouse lens cell lines that can be used for transfection studies and that will be useful in obtaining nuclear transcription factors. Currently, transfection studies involving reporter genes linked to lens specific promoters had to be carried out in a rabbit cell line. Most of the promoter regions of interest are from mouse since these can be used to make constructs for transgenic animals. Mouse lens cells were used as a starting material for protein purification to obtain nuclear transcription factors. We have recently established cloned lens cell lines from "immorto" mice that are also transgenic animals. These animals carry a temperature sensitive large T-antigen from SV-40 virus linked to a promoter activated by gamma interferon. By growing cells at permissive conditions, we are able to maintain an actively dividing population of cells. By switching to higher temperatures without interferon, the cells stop dividing and start to express lens specific properties. We are currently developing and studying these cells and the lens specific properties that they express. These cell lines will be used with a battery of constructs for transfection studies.